Thyroid gland activity and motor activity during dog ontogenesis]

The locomotor activity (LA) and the level of the protein-bound iodine (PBI) in the blood serum were investigated in 62 puppies at the age of 1--12 months. A parallel elevation of PBI and the LA was observed the first 4 months after birth. The second peak of the LA at the age of 7--9 months was not accompanied by any PBI rise. Inhibition of the thyroid function with mercasolyl increased the LA at the age of 1--3 months and decreased it at the age of 7 months. An increase of the LA one month after thyroidectomy was found at the age of 1 and 3.5 months. The activity of puppies operated on at the age of one month showed a sharp fall after 2--4 months. The data on various effect of thyroid hormones on puppies of different age pointed to the complex relation between the LA and the thyroid gland function.     

The effect of isoproterenol on fluid and electrolyte transport in the inner medullary collecting duct

In the late distal and cortical collecting tubule, which is the principal regulatory site for potassium (K) excretion, vasopressin stimulates, and epinephrine via beta-adrenergic action, inhibits K secretion. In the inner medullary collecting duct (IMCD) we have shown that vasopressin also stimulates K secretion. The present experiments were designed to determine whether the beta-adrenergic agonist, isoproterenol, would induce K reabsorption in the IMCD, and (or) prevent a secretory response to acute KCl infusion. Two groups of rats, with or without isoproterenol administration (3 micrograms/h), were subjected to retrograde microcatheterization of the IMCD before and during infusion of 0.83 mol/h KCl. Isoproterenol reduced plasma K concentration and urinary K excretion, but the response to acute KCl infusion was qualitatively similar to control. Isoproterenol decreased delivery of potassium, chloride, and fluid to the IMCD, there was no net transport of K along the duct in either group, and KCl infusion did not result in K secretion in either group. The results indicate that isoproterenol may inhibit K secretion in the late distal or cortical collecting tubule. However, there was no statistically significant difference in K transport along the IMCD between isoproterenol and control groups. Reduced sodium excretion, which was found during isoproterenol administration both before and after KCl infusion, was associated with no change in sodium delivery but with increased sodium reabsorption in the IMCD. This increased sodium reabsorption may be a direct effect of isoproterenol, or may be due to reflex cardiovascular adjustments associated with systemic actions of the drug.     

The effect of DOPA on the reciprocal inhibition of the innervation centers of antagonistic muscles in newborn rat pups]

In experiments on 5--7- and 16-day rat puppies with acute lesion of the spinal cord, by means of monosynaptic tests, studies have been made of the effect of DOPA on reciprocal inhibition of antagonist muscles. Test stimuli were applied to n. tibialis, conditioned ones--to n. peroneus. It was shown that the pattern of the effects depends on the action of the drug on the magnitude of the initial monosynaptic reflex used as a test. It the latter was initially inhibited, the conditioned stimulation resulted within the first 1-8 msec not in the development of postsynaptic inhibition, but in evident facilitation, which was longer in 5--7-day animals. The level of presynaptic inhibition was somewhat lower than the initial one, but exhibited longer duration. In case of facilitation of a control test after DOPA injection, configuration of reciprocal inhibition curves did not significantly differ from that obtained before administration of the drug.     

Kaliuretic response to potassium loading in amiloride-treated dogs.

To assess whether an intact mechanism of sodium transport in the distal nephron is a prerequisite for the development of a kaliuresis in response to an acute potassium load (0.4 M KCl, 1 ml/min), the effects of a simultaneous infusion of KCl and amiloride (1 mg/kg/h) were evaluated in anesthetized dogs. A major reduction in potassium excretion mainly due to a sharp decrease in urine K+ concentration to one tenth of control levels was found after amiloride. The simultaneous infusion of KCl and amiloride resulted in a rapid and major increase in kaliuresis that was accounted for mostly by the rise in urine K+ concentration. The increased kaliuresis after the acute potassium infusion was of similar magnitude when expressed as percent value of control to that previously reported in dogs not receiving amiloride; the absolute rates of K+ excretion, however, were only 2.7 and 7.3% (before and after KCl infusion, respectively) of the values in dogs not receiving amiloride. Our observations suggest that potassium infusion in the intact dog increases kaliuresis primarily as a result of a more favorable chemical gradient of this cation between blood and/or distal tubular cells and urine. Yet, when a chemical gradient is the only driving force of potassium secretion, as was the case in our amiloride-treated dogs, the absolute rate of kaliuresis is very modest. The presence of an unimpaired electrical profile and sodium transport mechanisms in the distal nephron, although not critical for the development of kaliuresis in response to a K+ load, accounts for a severalfold rise in renal potassium excretion above basal levels.     

Urinary kallikrein excretion after potassium adaptation in the rat

24-h urinary kallikrein excretion in male Sprague-Dawley rats was measured before and after 14 days with 100 mM potassium chloride as drinking fluid ad libitum. Urinary kallikrein excretion increased in K+-adaptation. The increase was greater when the rats were given distilled water rather than 100 mM sodium chloride to drink prior to the potassium chloride. The urinary potassium excretion increased in all rats studied. The urinary sodium excretion, urine volume and fluid intake increased significantly in rats that had distilled water to drink prior to the KCl. In marked contrast, when rats were offered NaCl prior to KCl, the urinary sodium excretion was unaffected while the urine volume and fluid intake decreased significantly. This study shows that prior NaCl intake abolishes the natriuretic and diuretic effects of KCl load and only suppresses the increase in urinary kallikrein excretion. This suggests that K+ secretory activity at the distal tubules is the major determinant of the release of renal kallikrein in the rat.     

Influence of Medetomidine on Acid-base Balance and Urine Excretion in Goats

Seven goats were given medetomidine 5 μg/kg as an iv bolus injection. Venous blood samples were taken repeatedly and urine was collected continuously via a catheter up to 7h after the injection. Medetomidine caused deep clinical sedation. Base excess, pH and PCO2 in venous blood rose after medetomidine administration. There were no significant changes in plasma concentrations of sodium, calcium, magnesium, creatinine or osmolality, whereas potassium and bicarbonate concentrations increased, and phosphate and chloride decreased. Medetomidine increased plasma glucose concentration, and in 4 of 7 goats glucose could also be detected in urine. Medetomidine did not influence urine flow rate, free water clearance, bicarbonate and phosphate excretion or pH, but renal chloride, sodium, potassium, calcium, magnesium and creatinine excretion were reduced. The results suggest that the metabolic alkalosis recorded after medetomidine administration is not caused by increased renal acid excretion.     

Volume and ion regulating renal functions in the big gerbil (Rhombomys opimus L.) and the water vole (Arvicola terrestris L.)

1. After iso-osmotic salt loading (1% NaCl, 1.25% KCl, 0.75% MgCl2 solutions, each load making up 5% body weight) the water voles excreted 66.2% sodium, 84.4% potassium, 18.8% magnesium over a 4 hr period. The big gerbil excreted 20%, 58.9% and 7.1% respectively over the same period. The volume of the water excreted was greater in the case of the water vole. 2. There were no considerable changes in plasma ion concentration in rodents of the species studied after salt loading. 3. The gerbils and water voles had no significant changes in the renal cortex electrolyte concentrations as a result of isotonic salt loads. The highest sodium cortico-papillar gradient was found in the gerbils when experimenting with the isotonic NaCl loading. It was somewhat lower with the KCl load, and significantly lower with water and MgCl2 loads. 4. Under the same experimental conditions, no major changes in the papilla sodium concentration were found in the water voles. 5. The concentrations of potassium, calcium and magnesium were practically alike in all zones of the renal tissue of both rodent species, ion loads producing no effect. 6. The comparison of the renal volume and ion regulating function in rodents with different urine osmotic concentration systems proves the independent existence of renal functions. The greater rate of renal fluid and ion excretion in the water voles is coupled with less specific ion regulation.     

Centrally applied atrial natriuretic factor diminishes bile secretion in the rat.

Little is known about the role of centrally applied peptides in the regulation of bile secretion. We previously reported that the intravenous injection of atrial natriuretic factor (ANF) reduces bile acid dependent flow without affecting portal venous pressure in the rat. In the present work, we studied the effects of centrally applied ANF on bile secretion and the possible pathways involved. Rats were cannulated in the brain lateral ventricle for the administration of 1, 10 and 100 ng/microl ANF. After 1 week, the common bile duct was cannulated and bile samples were collected every 15 min for 60 min after the administration of ANF. The excretion rate of various biliary components was assessed. Bile secretion experiments were also performed after bilateral truncal vagotomy or atropine administration to evaluate the participation of a vagal pathway. In addition, the role of the sympathetic system was addressed by combined administration of propranolol and phentolamine. Centrally applied ANF did not modify blood pressure but diminished bile flow and bile acid output. It also reduced sodium and potassium secretion but did not modify protein or phospholipid excretion. Neither bilateral truncal vagotomy nor atropine administration abolished ANF response. Furthermore, combined administration of adrenergic antagonists did not alter ANF inhibitory effect on bile flow. In conclusion, centrally applied ANF reduced bile acid dependent flow not through a vagal or adrenergic pathway in the rat, suggesting the involvement of a peptidergic pathway.     

Relationship of urinary kallikrein excretion to urinary potassium excretion during furosemide administration with and without amiloride

The relationship of urinary kallikrein excretion to urine volume, and to urinary sodium and potassium excretions was studied in normal rats during furosemide diuresis and superimposed injection of amiloride, a K+-sparing diuretic. Continuous infusion of furosemide increased urinary kallikrein, sodium and potassium excretions and the urine volume. Amiloride injection during furosemide diuresis caused further increase in diuresis and natriuresis, but a prompt decrease in urinary kallikrein excretion to basal level, and potassium excretion to below the basal level. The significant correlation of urinary kallikrein excretion to urinary potassium excretion, but not to urine volume and urinary sodium excretion after amiloride injection suggests that the major determinant of urinary kallikrein excretion is renal potassium secretion through a mechanism that is affected by amiloride.     

The effect of plasma potassium in determining normal rates of excretion of potassium in dogs.

Doses of 5-15 mmol KCl or KHCO3 (less than the daily intake in food) given by stomach tube or intravenous infusion, produced increases in plasma K and in K excretion, the time delay between change in plasma K and rate of excretion being minimal. Without doses of K salts in control experiments, plasma K concentration was about 4 mmol/1 and K excretion about 5 mumol/min. After doses of KCl or KHCO3, plasma K and rate of excretion of K both increased, increase of 0-5 mmol/1 in plasma K being associated with an increase of about 35 mumo1/min in K excretion. Increased excretion of K was accompanied by a small increase in Na excretion. Excretion of both C1 and HCO3 increased, C1 more after HCO3 more after KHCO3. The results indicate that within normal ranges, plasma K is an important factor determining the rate of excretion of K.     

Immunogenicity and safety of Vi capsular polysaccharide typhoid vaccine in healthy persons in Korea

The purpose of this study was to evaluate the immunogenicity and safety of Salmonella Typhi Vi capsular polysaccharide vaccine (Vi vaccine) in Korea. The immunogenicity of a single dose of Vi vaccine was evaluated in 157 subjects (75 children and 82 adults) before and at 1, 6, and 12 months after vaccination. Immunogenicity was measured with a passive hemagglutination assay (PHA), quantified as geometric mean titers (GMTs) and seroconversion rates. The safety of the vaccine was investigated by determining adverse reactions occurring within 4 h, 3 days, and 1 month after injection. The seroconversion rate for children and adults 1 month after vaccination was 96.92% and 89.02%, respectively. In the case of children, the GMTs of Vi antibodies before vaccination were 5.87 +/- 1.34 and 142.59 +/- 2.39 at one month after vaccination. For adults, the GMTs before and one month after vaccination were 5.58 +/- 1.28 and 58.56 +/- 3.67, respectively. Vi antibodies persisted for as long as 6 and 12 months after vaccination. All adverse reactions in adults and children were minor and did not require treatment. The Vi CPS vaccine was safe and immunogenic in adults and children older than 5 years.     

Various characteristics of the activity of skeletal muscles in humans and dogs during postnatal ontogenesis

At normal ambient temperatures, in absence of stress, in babies during first months of life (in contrast to less maturely born mammals), the respiratory activity of skeletal muscles is not realized, being observed only under stress conditions. In 1-1 1/2 months old puppies, after deafferentation of the hindlimb, the frequency of movements of a jerk type increases approximating the level observed in newborn animals. At normal ambient temperatures, these puppies exhibit respiratory activity of skeletal muscles which is not observed at this age in control animals.     

Apgar score after induction of anesthesia for canine cesarean section with alfaxalone versus propofol

The effects of alfaxalone and propofol on neonatal vitality were studied in 22 bitches and 81 puppies after their use as anesthetic induction agents for emergency cesarean section. After assessment that surgery was indicated, bitches were randomly allocated to receive alfaxalone 1 to 2 mg/kg body weight or propofol 2 to 6 mg/kg body weight for anesthetic induction. Both drugs were administered intravenously to effect to allow endotracheal intubation, and anesthesia was maintained with isoflurane in oxygen. Neonatal vitality was assessed using a modified Apgar score that took into account heart rate, respiratory effort, reflex irritability, motility, and mucous membrane color (maximum score = 10); scores were assigned at 5, 15, and 60 minutes after delivery. Neither the number of puppies delivered nor the proportion of surviving puppies up to 3 months after delivery differed between groups. Anesthetic induction drug and time of scoring were associated with the Apgar score, but delivery time was not. Apgar scores in the alfaxalone group were greater than those in the propofol group at 5, 15, and 60 minutes after delivery; the overall estimated score difference between the groups was 3.3 (confidence interval 95%: 1.6–4.9; P < 0.001). In conclusion, both alfaxalone and propofol can be safely used for induction of anesthesia in bitches undergoing emergency cesarean section. Although puppy survival was similar after the use of these drugs, alfaxalone was associated with better neonatal vitality during the first 60 minutes after delivery.     

Long-Term Responses to Loss of Renal Mass: Tubular Changes: Potassium Adaptation After Reduction of Nephron Population

Two weeks after 75 percent nephrectomy in rats fed a normal diet glomerular filtration rate was found to be reduced by 2/3 and there was no hyperkalemia. Normal K balance was maintained by a threefold increase of fractional urinary potassium excretion. When infused with 0.5 M KCl solution, both normal and 75 percent nephrectomized rats increased their fractional excretion, while normal rats kept on a very high K-diet did not further increase their fractional potassium excretion. Adaptation of fractional excretion to infused KCl was blunted in 75 percent nephrectomized rats given a low K diet.Addition of 0.1 M KCl to the drinking water resulted in a three- to fourfold increase of potassium intake in normal rats: within 7 days, the Na-K-ATPase in the outer medulla of the kidney rose by 30 percent but no change occurred in the cortex. Further increases in dietary K load induced an increase of Na-K-ATPase activity, both in outer medulla and cortex, but not in other tissues. After 75 percent nephrectomy, specific Na-K-ATPase activity increased by 20-25 percent in the outer medulla and in the cortex.Dietary K loading, in normal rats, also resulted in a large increase of net potassium secretion into the perfused colon and of specific Na-K-ATPase activity of the colonic mucosa. These effects of potassium loading were not abolished by adrenalectomy and were accompanied by an increase of transmural PD. It was concluded that chronic potassium loading may enhance secretion of potassium into lower nephron tubular fluid and into colonic contents by primarily stimulating the synthesis of Na-K-ATPase and the resulting increase of the number of pumping sites. 75 percent nephrectomy may induce similar changes in the remaining nephrons.     

Studies on renal excretion of potassium in the dik-dik antelope

1. In a study on the renal handling of potassium by the dik-dik antelope, plasma and urine samples were analysed for potassium, sodium and creatinine concentrations and osmolality during dehydration and intra-ruminal loading of potassium solutions. 2. The fractional excretion of potassium was 0.64 during the control period and rose up to as high as 2.3 during potassium loading. Urinary osmolality and potassium concentration decreased as the urine volume increased but the total amounts of potassium excreted were independent of urine volume. 3. Potassium loading led to a steady increase in its urinary excretion but a decrease in plasma potassium concentration was observed. This observation casts doubt on the hypothesis that alterations in potassium intake produce parallel alterations in plasma potassium concentration (which supposedly stimulates or depresses potassium excretion) and thereby maintain potassium homeostasis. 4. A possible alternative signal for increased potassium excretion following increased intake is discussed.     

The morphogenic effect of gonadotropic hormones on the Leydig cells of the boar testis. II. Effects of administration of chorionic gonadotropin after hypophysectomy. Effects in vivo and in organ culture

The longer ago the hypophysectomy has been performed, the more marked is Leydig cell atrophy in the testis. The effects of HCG on cellular morphology have been observed in vivo and in organ culture; qualitative quantitative and ultrastructural aspects were studied. In vivo, the effects of a daily injection of gonadotropin on the testis of 2 boars hypophysectomized 3 1/2 months ago are shown. Markedly atrophied cells are strongly stimulated by HCG during the 15 first days (the cell and nucleus recover nearly to standard size, with the typical histological and ultrastructural appearance with all the cell organelles which characterize a functional steroid cell). Then after 1 1/2 month injection it decreases again to the initial state (very small size cytoplasm strongly reduced with very low organelle content). The number of the Leydig cells is maintained during the first 15 days, then it progressively decreases. The effects of HCG on the testicular tissue of 4 boars were studied in organ culture. Interstitial tissue with a greater or lesser degree of atrophy was examined experimentally (1 month, 3 months and 4 months after hypophysectomy) in order to prove a possible irreversibility of the effects of hypophysectomy. In each case, cell changes were studied according to the duration of the culture. Control cultures without HCG in the medium were set up simultaneously. 1 month and/or 3 months after hypophysectomy, the Leydig cells in culture progressively recover the size and the histological and ultrastructural appearances of a typical Leydig cell. After 16 days of culture, the stimulation is highest, as in vivo. The number of Leydig cells is maintained. From the 17th day stimulation decreases and the cell enters a new atrophy phase. In the anhormonal control medium the atrophy continues as long as the culture is maintained, and the number of Leydig cells decreases. 4 months after hypophysectomy, stimulation in culture is still possible during the first 10 days (proved by the same tests); however the size of the cell remains small compared to the normal; then it atrophies again quickly. In this case the hormone does not maintain the number of the Leydig cells. In the control cultures, slight response of the cell is observed, but this effect is limited and disappears a few days later; the number of the cells rapidly decreases. It has been shown that markedly atrophied Leydig cells can highly be stimulated during the first 2 weeks under the influence of HCG as well in vivo as in organ culture. The lability of the effect is not yet explained. 4 months after hypophysectomy, stimulation is not so effective.     

The effect of DOPA on segmental reflexes in rat pups]

In acute experiments on spinal 5-30-day rat puppies, studies have been made of the effect of DOPA (100 mg/kg intraperitoneally) on monosynaptic reflex in extensors (evaluated by parameters of H-reflex) as well as on polysynaptic segmentary reflexes. In 5-7-day animals, mainly the inhibitory effect was observed with a short phase of facilitation of monosynaptic reflex. From the 10th day, facilitatory effect of DOPA becomes a predominant one reaching maximum to the 16th day. Within first 16 days of postnatal life, DOPA exhibits facilitatory effect on short-latent polysynaptic reflexes and inhibits long-latent ones. To the 30th day, reactions which are typical of adult animals are observed: inhibition of short-latent and facilitation of long-latent polysynaptic discharges. The data obtained indicate that in early postnatal development the effect of DOPA on mono- and polysynaptic reflexes qualitatively differs from that in adult animals.     

Electrophoretic and immunochemical research of rat urine proteins in dynamics after intravenous injection of thorium dioxide (thorotrast)

Rats were treated with a single intravenous injection of thorotrast (thorium dioxide)--the source of alpha-rays. Dynamic investigation of urine protens of rats by methods of electrophoresis and immunoelectrophoresis was carried out during 22 months after thorotrast injection. Already the month after drug injection the selectivity of tubular reabsorbtion was disturbed. Three months after thorotrast injection the content of urinal proteins of tissue (in particular renal) origin was decreased. Finally the selectivity of renal filtration of proteins was damaged 4-6 months after thorotrast introduction. Serum proteins which were absent in normal urine (for example transferrin and lipoproteins) appeared in urine of affected rats. The urine proteins of serum origin were less degraded than those in normal urine. The alterations of glomerular filtration was increased up to 20-22 months when the spectrum of urine proteins became similar to the spectrum of serum proteins. The death of treated rats was occurred in this period. Thus the monitoring of urine proteins of rats treated with alpha-ray producing preparation throtrast allows to register the successive alterations of reabsorbtion, excretion and filtration functions of kidney.     

Atrial natriuretic factor inhibits noradrenaline release in the presence of angiotensin II and III in the rat hypothalamus

1. Atrial natriuretic factor effects on neuronal noradrenaline release evoked by angiotensin II or III and high potassium solution plus angiotensin II and III in the rat hypothalamus were studied.2. Atrial natriuretic factor (10 nM) did not modify spontaneous noradrenaline release. On the other hand, the atrial factor diminished the increase of noradrenaline release induced by both angiotensin II (1 μM) or angiotensin III (1 μM).3. Ten nanomolar ANF reduced the amine output induced by 100 nM KCl. Both angiotensins enhanced the 3H-noradrenaline secretion stimulated by high potassium solutions. When atrial natriuretic factor was added to the medium containing the depolarizing KCl solution plus angiotensin II or III (1 μM), the diminishing effects were greater than when the atrial factor was added to the depolarizing solution alone.4. Our results suggest that atrial natriuretic factor effects on noradrenaline release, evoked by angiotensin II, III and KCl, may be involved in the regulation of the central catecholamine pathways and sympathetic activity.     

Renal regulation of potassium homeostasis in calves in the first week of life including the role of atrial natriuretic peptide

The experiment was carried out on 10 clinically healthy Polish-Friesian var. Black-and-White cow calves, during the first seven days of postnatal life. The results indicate that renal removal of potassium depends primarily on the quantity reabsorbed in the tubules, whereas clearance of the electrolyte, due to stable levels in the blood plasma, depends on the amount excreted in the urine. With stable tubular reabsorption of potassium, a relatively unchanging amount of excreted potassium was observed in the urine. However, reduced tubular reabsorption caused a significant increase in excretion and clearance of the electrolyte. Changes in the amount of filtered potassium play a minor role in the regulation of excretion. Small changes in the blood plasma potassium concentration observed primarily resulted from changes in glomerular filtration rate and tubular reabsorption, since the concentration of electrolyte in the blood after birth remained within the physiological range. The results ofthis study suggest that neonate calf kidneys are sufficiently prepared to regulate kalemia. Atrial natriuretic peptide is not directly involved in the regulation of tubular reabsorption of potassium in calves in the first week of life, although it is highly likely that the peptide is involved in the excretion of potassium in the urine in calves during the first seven days of life.